From: Ben Creisler
bcreisler@gmail.com
A new online paper:
Qi Zhao, Michael J. Benton, Corwin Sullivan, P. Martin Sander & Xing Xu (2013)
Histology and postural change during the growth of the ceratopsian
dinosaur Psittacosaurus lujiatunensis.
Nature Communications 4(2079)
doi:10.1038/ncomms3079
http://www.nature.com/ncomms/2013/130628/ncomms3079/full/ncomms3079.html
A few dinosaurs are inferred to have undergone an ontogenetic shift
from quadrupedal-to-bipedal posture, or vice versa, based on skeletal
allometry. The basal ceratopsian Psittacosaurus lujiatunensis is
considered to have been mainly bipedal as an adult. Here we infer a
postural shift in this species based on a novel combination of limb
measurements and histological data. The forelimb is strongly
negatively allometric relative to the hindlimb, and patterns of
vascular canal orientation provide evidence that growth of the
hindlimb was particularly rapid during the middle part of ontogeny.
Histology also makes it possible to determine the ontogenetic ages of
individual specimens, showing that the forelimb-to-hindlimb ratio
changed rapidly during the first or second year of life and thereafter
decreased gradually. Occurrence of an ontogenetic shift from
quadrupedality to bipedality was evidently widespread in dinosaurs,
and may even represent the ancestral condition for the entire group.
A news release:
http://phys.org/news/2013-06-exploring-dinosaur-growth.html